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skiatook_bu

Drive Shaft snapped

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skiatook_bu

Any ideas on the cause of this? We were in deep water, no ballast, accelerating off idle and "POP". :cry: I have maybe one season of use on this full driveline replacement with all new parts.

New drive shaft, coupler, coupler bolts, dripless shaft seal, strut, prop, and rudder.

20150614_001033.00_00_25_23.Still002.jpg

20150614_001033.00_00_07_00.Still004.jpg

20150614_001033.00_00_33_28.Still006.jpg

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Afun

First One I See....

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04 VLX WINDERMERE UK

I would say its a fatigue break, from the gear box/v drive not been correctly lined up? Small stress imposed on every rotation that results in failure? Gap needs to equal before the bolts are lined up.

it will be interesting to see what others think?

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justgary

It broke right where the taper meets the key slot, which is the weakest point. It's either misalignment or an inferior aftermarket part.

Did you replace it yourself, or have it done professionally?

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skiatook_bu

I had it all put in by the marina, when I hit something underwater a few years ago.

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302Zapper

Cheap Chinese steel?

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GreenMan

Ouch! Agree with others - it's either an inferior quality shaft or significant misalignment that results in work hardening of the shaft until it fails. Or a combination of both.

Would be real interesting to offer up a new shaft and check the coupling alignment...

Are all the engine mounts sound? No lock nuts rattled loose, bolts rattled out of the engine or gearbox etc that could result in alignment changing over time?

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Steve B.

Prior to this, how was the feel of the boat? Little, or a lot of vibration?

I'm thinking faulty shaft, but....

Steve B.

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skiatook_bu

No vibration

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skiatook_bu

I took the coupler off today and shot a better picture of it. How critical is the .003 tolerance on the alignment. I was with the mechanic when he aligned the engine, but he did not use any feeler gauges when it was installed. I have had problems with the bolts coming loose in the past. I think he took off the washers the last time they were tightened.

I also think the bolts/nuts are backward. The head of the bolt hits the coupler this way and would have to be tightened on the nut on the hard to reach side.

I ordered another A.R.E. double taper drive shaft system and new coupler bolts from skidim (Elbert's)

IMG_3592.JPG?gl=US

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GreenMan

The alignment is pretty important. The smaller the error, the longer the shaft will last.

On my RLXI it's pretty easy to get a good visual on the coupling assembly during alignment and might be satisfied without using feeler gauges but on a vee drive (I've never done one...) I imagine it's all but impossible to get a good look at it and feeler gauges or similar would likely be essential to assure reasonable alignment?

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justgary

I don't see how to get really good alignment without feeler gauges. On my direct drive, moving the front of the engine 0.030" is enough to put it out of tolerance. Remember also that the alignment is vertical as well, so your man would have to visualize the side of the coupler too. Can he see the side well enough to judge the gap?

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malibuparadise

did a shaft/coupler alignment without using a feeler gage, wow....never ever heard of that--not with a 3 thousandth or better fit....it's an iterative adjustment process....

Edited by malibuparadise

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obski

I broke 2 drive shafts on my 01 SS VLX. Turned out it was a small misalignment of the engine.

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skiatook_bu

I installed the new shaft yesterday. It is probably 1/2 inch off on lining up the couplers. Hopefully, I can get everything lined up today and figure out how it became so far out of alignment.

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GreenMan

Wow, that'a a lot of misalignment!

Surely that means one of two things - either your new drive line was never aligned properly at installation or the new strut has been bent since installation. Is the strut still firmly attached to the hull (glued and screwed)? Is the error mostly side-to-side or up-down? Moot point really - it is what it is.

There's plenty of range of movement in the engine mounts so just going to have to work away at it with pry bar and hammer on the sliding parts of the mounts for horizontal movement and the adjusting nuts for vertical movement. And use feeler gauges for the final setup!

It may be that in a past life the engine was aligned to a bent strut and when your new (straight) strut was installed the shaft/coupler was now in the correct place but the engine remained off to one side?

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skiatook_bu

I had the whole driveline replaced 3 years ago. Strut, shaft, shaft seal, rudder, wedge, and the bottom of the boat reglassed. I was there when it was aligned with all the new parts and I have all the old parts that were replaced.

Maybe it twisted when the shaft broke. The 2 bolts in the coupler were loose, one broken and one missing.

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williemon

Need to make sure the shaft is centered in the log. The strut pretty much sets that. Then align engine to the properly centered shaft.

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skiatook_bu

Coupler alignment way off with the new drive shaft installed.

IMG_3645.JPG

Shaft is slightly off center

IMG_3668.JPG

Bolts inside look good on the strut

IMG_3651.JPG

Strut hasn't moved where it was mounted.

IMG_3667.JPG

I did not hit anything to twist the strut, but it definitely looks shifted port side 1/4 inch or so at the coupler. Maybe this happened when the shaft broke and the coupler jumped on the running driveline. One bolt was sheered off, one was missing, the other two were a little loose.

Should I try to twist the strut back toward starboard while on the boat? or is it close enough to just move the engine to match. I would think the distance the prop would move would be minor and as long as it doesn't rub, lining up the engine to the strut would be the best option.

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justgary

I removed my strut and straightened it on a press stand. I doubt that you can effectively do the job while it is on the boat, but it is certainly worth a try. An old shaft would work great as a prybar.

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GreenMan

I guess if you assume that the shaft should be central in the hull opening, you would ideally first centralise the shaft and align it to the drive coupling maybe by re-mounting the strut and then fine-tuning the engine alignment. FWIW, the shaft on my boat isn't central in the hull opening.

That said, removing and remounting the strut may be a bit of a job although seemingly made easier because it appears that your HDS box has been removed and replaced with a 'conventional' log / shaft housing? Normally the strut mounting bolts are within the HDS box and there are no screws around the shaft opening.

Alternatively, it probably isn't an issue if the engine is just aligned to the present shaft position...?

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justgary

^^^^^ What GreenMan said.

I would ignore the hull cutout and concentrate on the shaft log and strut, then move the engine to match that alignment.

By the way, I found my strut very easy to remove by myself by locking the wrench against the side of the HDS box (which you may not have now) and sitting under the boat to turn the screws. I got a helper to hold the wrench when I put it back on so I could concentrate on keeping it aligned with the shaft.

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malibu2004

Like others have said don't worry about the drive shaft being centered in the hole. Before you mess with the strut I would see if you can align the motor.

The .003 alignment is extremely important and you can't do it with your eyeball. If your mechanic did do the eyeball alignment he is an idiot.

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williemon

I did not know the strut on mine was out as bad as it was. Both the old one and the new one. I can only assume that the the issue came from the factory. The strut situated itself where the shaft was pressing down and to the side in the log. I could not tell this until I just happened to pull the rubber hose with the shaft packing forward to expose the end of the log. Then I saw the damage. I had to shim and tweak the brand new strut.

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skiatook_bu

I installed the new drive shaft, but I could not get the alignment 100%. I am just not sure which nuts to turn which way and how far. I have about a .010 gap at the top. I literally worked on it 3 different days.

I sent the prop to OJ and they said the hub was damaged and it was unrepairable. I test drove the boat today and had a bad vibration off idle, so my backup prop (previously repaired) is out of balance, I need a new strut, or I bent the new shaft tweaking the motor mounts too far. I have new vesconite? bushings on the way in the next day or so.

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